<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <script src="https://cdn.staticfile.org/react/16.4.0/umd/react.development.js"></script>
  <script src="https://cdn.staticfile.org/react-dom/16.4.0/umd/react-dom.development.js"></script>
  <script src="https://cdn.staticfile.org/babel-standalone/6.26.0/babel.min.js"></script>
  <title>Document</title>
</head>

<body>
  <div id="render"></div>
  <script type="text/babel">
    class Clock extends React.Component {
      constructor() {
        super()
        this.state = { age: 18 }
      }
      addAge() {
        console.log(this)
        // this.setState({
        //   age: ++this.state.age
        // })
        this.setState(res => ({
          age: ++res.age
        }))
      }
      render() {
        return (
          <div>
            <h1>我今年{this.state.age}岁了</h1>
            <button onClick={(e) => this.addAge(e)}>快快长大</button>
          </div>
        )
      }
    }
    ReactDOM.render(
      <Clock />,
      document.getElementById('render')
    )
  </script>

</body>

</html>